Talc, Mg.sub.3 Si.sub.4 (OH).sub.2, is a natural mineral, with a sheet silicate structure. It has a platy morphology and is oleophilic/hydrophobic being wettable by oil rather than water. Talc provides good lubricity or slip and has acceptable fragrance retention. Known talcum powder formulations vary in complexity from merely talc and perfume to those having numerous components, especially in some products directed towards specific use.
It is found that the lubricity of talc is affected by repeated exposure to moisture, constant wetting and due to the formation of a thin layer of perfume molecules on the surface of talc platelets which induces stickiness. This causes a morphological change of the talc from a platy morphology to aggregates or globule formation which retard the flow property, hamper the spreadability (surface coverage) and may also be responsible for retarding the release/impact of perfume. This effect becomes increasingly acute for talcum powders formulated with other additives such as calcium carbonate, zinc stearate etc., and on increasing the perfume dosages in the formulation. Traditionally talcum powder manufacturers have been using super adsorbers such as cross linked carbomethyl cellulose and starch based derivatives in an attempt to overcome the aforementioned problems. However, these additives are not found to demonstrate significant improvement over talcum powders formulated without such super adsorbers.
U.S. Pat. No. 4,000,317 discloses the use of pyrogenic silica of spherical shape and very small particle size for adsorption of sebum, the oily material secreted by the sebaceous glands on the human face. However the said patent does not provide for any modification directed to improvement in talc properties for use in skin formulations and the like.
U.S. Pat. No. 5,683,706 discloses powder compositions containing high levels of talc, low levels of titanium dioxide and a sebum absorbing material to provide compositions having improved skin coverage, uniformity and duration of wear. However, the said patent also does not disclose or teach for improvement and/or modification in talc properties to achieve combination of desired beneficial effects in talc formulations for cosmetic and like applications. Moreover talc and sebaceous absorbing material used in the said patent would phase separate on account of bulk density and particle size distribution differences affecting talc benefit properties in the formulation.
It is found that talc as used for talcum powder has markedly inferior moisture absorbency. This further decreases due to the hydrophobic effect of perfume when it is sprayed on talc. Talc as such is a poor vehicle for retaining perfume. As such talc cannot be used for delivering deodorancy benefits.
It is thus an objective of the present invention to provide talc in a form whereby its lubricating (free flowing), moisture adsorption capacity, oil retention capacity, fragrance retention properties etc. are improved for use in various cosmetic and like applications.
Another object of the present invention is to provide a process for the manufacture of talc at least partly coated with porous material such as herein described, which provides talc having improved lubricating, moisture adsorption capacity, oil retention capacity, fragrance retention properties etc. for use in various cosmetic and like formulations.
Yet another object of the present invention is to provide a synergistic combination of talc coated and/or precipitated with porous material such as herein described which would have improved lubricating, moisture adsorption capacity, oil retention capacity, perfume retention capacity and thus suitable for use in various cosmetic formulations such as talcum powder, deodorant, deo-talc and the like.
Yet a further object of the present invention is directed to provide for synergistic talcum powder formulation comprising talc coated with porous material such as herein described.